title: Reproductive isolation between phylogeographic lineages scales with divergence.
abstract: Phylogeographic studies frequently reveal multiple morphologically cryptic lineages within species. What is not yet clear is whether such lineages represent nascent species or evolutionary ephemera. To address this question, we compare five contact zones, each of which occurs between ecomorphologically cryptic lineages of skinks from the rainforests of the Australian Wet Tropics. Although the contacts probably formed concurrently in response to Holocene expansion from glacial refugia, we estimate that the divergence times (τ) of the lineage pairs range from 3.1 to 11.5 Ma. Multi-locus analyses of the contact zones yielded estimates of reproductive isolation that are tightly correlated with divergence time and, for lineages with older divergence times (τ > 5 Myr), substantial. These results show that phylogeographic splits of increasing depth represent stages along the speciation continuum, even in the absence of overt change in ecologically relevant morphology.
authors.affiliation: Museum of Vertebrate Zoology, University of California, , 3101 Valley Life Sciences Building, Berkeley, CA 94720-3160, USA, Department of Integrative Biology, University of California, , 1005 Valley Life Sciences Building, Berkeley, CA 94720-3140, USA, Research School of Biology, The Australian National University, , Building 116, Acton, Australian Capital Territory 0200, Australia.
authors.forename: Sonal
authors.initials: S
authors.lastname: Singhal
authors.forename: Craig
authors.initials: C
authors.lastname: Moritz
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism; D005260:Female; D005819:Genetic Markers; D014644:Genetic Variation; D008116:Lizards / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D011793:Queensland; D060047:Reproductive Isolation; D017422:Sequence Analysis, DNA; D014329:Tropical Climate
chemical_list: D004272:DNA, Mitochondrial; D005819:Genetic Markers
keywords: cryptic species; demographic reconstruction; hybridization; phylogeography; reproductive isolation; suture zone